The mother of an Oregon boy missing for 53 days tearfully addressed her son during a Tuesday news conference, telling him not to give up hope, while investigators doubled a reward for information in the case.

The Multnomah County Sheriff's Department said "significant progress" was being made in the search for 7-year-old Kyron Horman, but declined to offer details. The reward for information leading to Kyron's whereabouts was increased from $25,000 to $50,000.

Desiree Young broke down while sharing a message for her son with reporters, sobbing: "We love you Kyron. Never give up hope. We are all coming to get you to bring you home."

Kyron vanished June 4 after attending a science fair at Skyline Elementary School in northwest Portland. The case has taken many twists in the weeks since, many of them centered on his stepmother, Terri Horman.

Terri Horman has not been named as a suspect in Kyron's disappearance, and she has never spoken publicly about it.

The boy's father, Kaine Horman, filed for divorce from Terri Horman in late June, claiming he believes she has information about his son's disappearance. He also says investigators told him that last year Terri Horman tried to hire somebody to kill him. The alleged plot was uncovered during the investigation into Kyron's disappearance, Kaine Horman's court filing said.

Terri Horman hasn't been charged with anything, and her attorney, Stephen Houze, has repeatedly declined to comment. However, he said in court earlier this month Terri Horman is being subjected to a "witch hunt."

Court documents also say Terri Horman engaged in a sexual relationship with a former acquaintance of her husband's during the initial days of the search for Kyron. The relationship included the exchange of lurid images by cell phone, or "sexting," court records said.

Kaine Horman was granted a court order to have Terri Horman leave the family home. She has reportedly been living in southern Oregon with her parents.

"Significant progress in this case is occurring in that tips are being reviewed, leads are either being considered, worked or have been ruled out," sheriff's Capt. Monte Reiser said at Tuesday's news conference.

However, Reiser also said investigators are prepared for a "long-term effort" in the search for Kyron.

Kaine Horman and Young stood behind authorities at the news conference.

"Our goals are to expedite the search for Kyron, to bring him home as quickly as possible, and to bring justice to any person responsible for his disappearance," Young said.